Polysilicon has been used as a starting material of semiconductors or wafers for solar generation, and must be in a highly pure form. From the standpoint of avoiding a decrease in the electric properties such as resistance, in particular, the polysilicon must be prevented from being mixed with metal impurities as much as possible.
The polysilicon is, usually, produced by reducing a silicon compound such as trichlorosilane with hydrogen or the like, and is obtained in the form of rods or a large masses. The polysilicon obtained in such a form is crushed, and from which contaminants adhered thereto during the crushing are removed by etching. The polysilicon is then passed through the steps of washing with water and drying, and is conveyed to the step of producing single crystals of silicon. In these steps, there are used various metal members (such as chute, hopper, crusher bed, etching vessel, water-washing vessel, drier, etc.), and the polysilicon must be prevented from being contaminated with metals as a result of coming in contact with these metal members.
To avoid the polysilicon from being contaminated with metals, the simplest means is to use resin members instead of metal members. For example, a patent document 1, paragraph [0003], teaches the use of resin members at portions where metals come in contact with the polysilicon in addition to teaching the problem of contamination of the polysilicon with metals.